The present invention relates generally to magnets, and more particularly to reducing 3D (three-dimensional) magnetic field inhomogeneity in a magnet having opposing pole pieces.
Magnets include those having spaced-apart first and second pole pieces with generally opposing first and second pole faces, such as (but not limited to) "C"-shaped magnets. Some magnet applications, such as magnetic resonance imaging (MRI) for medical diagnostics, employ superconducting magnets to generate a high strength magnetic field within an imaging volume. The imaging volume must have a low magnetic field inhomogeneity for high quality imaging. Known techniques for reducing the magnetic field inhomogeneity within the imaging volume include using shimming rings attached to each pole face to reduce axisymmetric magnetic field inhomogeneity and using shims attached to the shimming rings to reduce 3D (three-dimensional) magnetic field inhomogeneity. What is needed is a magnet which is designed to better reduce magnetic field inhomogeneity which, in MRI applications, will improve imaging quality.